Apparatus for and method of producing curved electrotypes



Nov. 26, 1957 H. L. BISHOP 2,814,089

APPARATUS FOR AND METHOD OF PRODUCING CURVED ELECTROTYPES Filed July 12, 1954 2 Sheets-Sheet l IN V EN TOR;

HIS ATTORNEYS HOMER BISHOP Nov. 26, 1957 H. L. BISHOP 2,814,089

APPARATUS FOR AND METHOD OF PRODUCING CURVED ELECTROTYPES Fild July 12, 1954 2 Sheet s-Sheet 2 VIII/III: 74 70 1MHMMIMMMHKHHMHIM INVENTOR. T 3 1o 3+H0MER L. BISHOP United States APPARATUS FOR AND METHOD OF PRODUCING CURVED ELECTROTYPES Application July 12, 1954, Serial No. 442,741

7 Claims. (Cl. 2921) This invention relates to apparatus for and method of producing curved electrotypes and more particularly to apparatus for and method of condensing or compressing the backing material used in casting electrotypes cast in a curved mold.

In the manufacture of electrotypes, it is customary to place a shell forming the face of the electrotype in some type of a mold cavity and then cast a backing material on the rear of the shell. Various types of materials may be used, such as an alloy consisting of lead, tin and possibly some antimony. This backing material is applied to the rear of the shell by adding the molten metal. Theoretically, the backing metal should be united or bonded to the rear of the shell without any voids or blow holes and without any undesirable depressions in the face of the shell. However, in actual practice, voids may be formed, possibly by gases or air trapped by the molten metal, leaving what is generally referred to in the art as soft spots in the electrotype plate. Upon the plate being used on a printing cylinder, the face of the electrotype fails, possibly by the backing metal permitting the face of the electrotype to be depressed, resulting in a pale or a blank area in the impressionmade by the electrotype plate. When the electrotype plate is cast in the flat, the rear of the backing metal may be compressed by the device disclosed in the Bishopv Patent No. 2,580,723, patented January 1, 1952, for Preliminary Finishing Machine. The disclosure in this patent has gone into extensive use in the industry and is doing an excellent job solving the problem of compressing the backing metal on a flat electrotype- However, the apparatus and method disclosed in the aforementioned patent cannot be used in a device Where the electrotype has been cast while curved.

An object of this invention is to provide apparatus for compressing the backing metal on electrotypes that have been cast while curved. This has been accomplished by urging or forcing a compression roller into contact with the rear of the backing metal by means of a weight before removing the electrotypes from the cylinder used in casting. 7

Another object of this invention is to provide a compression wheel that is fed through a cylinder in such a manner that the compression wheel generates a helical path while passing from one end of the cylinder to the other and wherein a constant pressure is applied to the compression roller.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

Referring to the drawings, Figure l is a perspective view of the apparatus used in compressing electrotypes cast while curved.

Figure 2 is an enlarged detail view of a portion of the mechanism used in compressing the electrotype.

Figure 3 is a longitudinal cross sectional View, taken substantially on the line 3'-3 of Figure 4.

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2,814,089 Patented Nov. 26, 1957 ice Figure 4 is a transverse, cross sectional view, taken substantially on the line 44 of Figure 3.

Figure 5 is a fragmentary, detail view of a locking mechanism.

Figure 6 is a top plan view of the locking mechanism.

In the drawings, the reference character 10 indicates a cylindrical mold member or drum provided with suitable marginal bearers that have not been shown in detail. The cylindrical mold member 10 is supported upon a plurality of rollers 12 mounted upon shafts 14 extending parallel to the longitudinal axis of the cylindrical mold and journalled in suitable bearings that have not been shown.

The drum 10 is driven through a driving means consisting of one or more drive wheels 16, only one of which has been shown, rotated through a driven shaft 18 driven from any suitable source of power. When using this circular mold, the shells are first placed throughout the inner periphery of the mold. Then the cylindrical mold is rotated at a speed sufiicient to cause the backing metal when it is poured into the mold to be acted upon by centrifugal force, so as to be held in contact with the inside periphery of the drum and in contact with the shells mounted therein until the metal solidifies to the extent that the metal does not flow.

In the past, when the metal has solidified, the bearers at the end of the drum are removed, the drum is then removed and raised on end. By merely tapping the end of the cylindrical cast electrotypes, the electrotypes drop out of the drum or mold. The cast cylindrical series of electrotypes are then severed from each other. The process described thus far has merely been described for the purpose of illustration and is conventional in the art. The electrotypes produced by this method, theoretically, should be perfect. However, this is not the case, in that there are soft spots in the metal, which may be caused by voids or blow holes or foreign matter that may cause a failure in the electrotype when put to use.

Before removing the shells from the mold, the device disclosed hereinv compresses and condenses the backing metal throughout the entire area by exerting a uniform pressure on all areas on the rear surface or inner surface of the cast material. The apparatus and method of doing this will now be described.

A pair of standards 30 and 32 are located at opposite ends of the cylindrical drum or mold member. The standard 30 has pivotally mounted thereto a bracket 34 having fixedly attached thereto a pair of parallel rail members 36 and 38. The opposite ends of the rail members 36 and 38 are held in fixed spaced relation by a bracket 40. The end of the rail member 36 projects beyond the bracket 40 and beyond the end of the rail member 38. The end of the rail member 36 is removably mounted upon the standard 32 and locked in position by means of a cam 50 provided with a cam surface 52 used in locking the end of the rail member 36 in position.

The rail members 36 and 38 support a carriage mechanism 60. This carriage mechanism includes a carriage member 62 provided with a transverse groove 64 in the upper surface thereof and a pair of transverse grooves 66 in the bottom. Each of these grooves support a roller bearing 68, the roller bearing in the groove 64 engaging the under side of the rail member 38 and the two roller bearings 68 in the grooves 66 riding upon the rail member 36. The carriage member 62 includes a pair of up- Wardly directed flanges 70. The distance between the upper portions of the flanges 70 is spanned by a threaded nut member 72 threadedly engaging a feed screw 74. One end of the feed screw 74 is journalled in a bracket '7 6 fixedly mounted upon the one end of the rail member 38. The opposite end of the feed screw 74 is driven by an electric motor through a suitable gear mechanism 78.

.A block 110, located above the wheel 100 and fixedly attached to the side members 94, is biased by a lever 112 mounted in an aperture in the block 110. This lever may be held in position by suitable set screws 114. This bar, as best seen in Figure 1, projects through a slot 120 in the standard 30 and supports an adjustably mounted weight 122.

As may best be seen by referring to Figure 2, the wheel 100 is offset, so as to be located a considerable distance to the left of the pintles 90. By this arrangement, it may be seen that the weight 122 acts on one end of the lever, .so as to exert a pressure on the wheel 100 fulcrumed about the pivots 90. By selecting the proper dimensions, it may be readily seen that a tremendous force may be exerted upon the wheel 100. This wheel 100 rests upon the inside or inner surface of the backing metal 140 located on the rear of the shell 142 mounted in the drum or mold member 10.

In Figure 4 voids 144 have been shown, greatly enlarged for the purpose of illustration, which voids should be eliminated. As the wheel 100 passes over such voids, it can readily be seen that the metal overlying the voids will be completely compressed, so as to fill these voids with metal.

A pneumatic or hydraulic cylinder 150 mounted upon the standard 30 and provided with a piston rod 152 may be used to raise the lever 112 and thereby release the pressure upon the wheel 100. As soon as the pneumatic or hydraulic mechanism releases the lever 112, a force is exerted upon the wheel 100, so as to cause the wheel 100 to compress the metal 140 underlying the wheel.

While one wheel or roller 100 has been described for applying pressure, it is to be undersood that the invention also includes the use of more than one. For example,

two or any desired number may be used, positioned in any sequence or manner desired, without departing from the spirit of the invention.

Before releasing the force applied to the wheel 100, the drum 10 is put into motion, that is, rotated at a suitable rate of speed. The piston rod 152 is then slowly released so as to cause the weight 122 to exert a force upon the wheel 100, moving this wheel into contact with the rear of the backing metal 140. At this time the motor 80 is energized. This results in the wheel 100 progressively advancing from one end of the drum to the other, sweeping out a helical path on the rear surface of the backing metal 140. By so doing, it is possible to compress the entire rear surface of the backing metal.

When the wheel has traversed the area on the rear of the cast metal, the motor 80 may be reversed, so as to go over the rear of the cast metal a second time. Upon the rear of the cast metal being compressed throughout its entire area, the force exerted upon the wheel 100 may be released by actuating the piston rod 152 upwardly. The cam or latch member 50 may then be rotated to release the end of the rail member 36. Then, by permitting the standard 32 to be rotated about the pivot 160, the drum 10, with the cast electrotypes therein, may then be removed, so as to permit the drum to be raised on end to remove the cast electrotypes from the shell.

Within the purview of this invention, any suitable mechanism for exerting a pressure against the roller may be used instead of the specific structure shown. The force exerted upon the roller may be varied by adjusting the weight, either longitudinally on the supporting rod, or by increasing or decreasing the weight thereof. The roller may be fed through the drum, so as to generate a helical path, then the rails supporting the carriage may be raised and the roller returned by reversing the direction of rotation of the feed screw and by changing the rate of speed thereof, so as to rapidly return the wheel. The peripheral contour of the roller used in compressing the metal is selected so as to efiectively compress the metal. By changing the ratio of the speed of the drum with respect to the speed of the feed screw, the pitch of the helical path generated by the roller may be altered to accomplish the desired results.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. Method of producing curved electrotype plates and condensing and compressing backing material thereon, said method including the steps of placing shells within a cylindrical drum, casting molten backing material on the rear of the shells, applying centrifugal force to the backing material to uniformly disperse the backing material over the rear surface of said shell, cooling said backing material, compressing the backing material by rotat ing said electrotype plate while in said cylindrical drum, applying pressure to said backing material, slowly moving said pressure horizontally throughout the width of said electrotype plate thereby forming a helical compressed path throughout the rear surface of the backing material.

2. Method of producing curved electrotype plates and condensing and compressing backing material upon the same, said method including the steps of placing shells within a cylindrical drum, casting molten backing material on the rear of the shells, applying centrifugal force to the molten backing material to uniformly disperse the same over the rear surface of said shells, hardening said backing material to form an electrotype plate, compressing the backing material by rotating said drum and said electrotype plate, and applying pressure upon a small portion of said electrotype plate, slowly shifting said pressure horizontally throughout the width of said electrotype plate, thereby forming a helical compressed path throughout the surface of the backing material.

3. Method of producing curved electrotype plates and condensing and compressing backing material by the use of a pressure roller, said method including the steps of placing shells within a cylindrical drum, casting molten backing material upon the rear surface of the shells, applying centrifugal force to the molten material to disperse the same uniformly over the rear surface of said shell. hardening said backing material, compressing the cast backing material by rotating said electrotype plate in said cylindrical drum and applying roller pressure upon a small area of the backing material of said electrotype plate while slowly moving said roller axially throughout the width of said electrotype plate, thereby forming a helical compressed path throughout the rear surface of the backing material.

4. Method of producing curved electrotype plates and condensing and compressing backing material upon the same, said method including the steps of placing shells within a cylindrical drum, introducing molten backing material on the rear of the shells, applying centrifugal force to said backing material to uniformly disperse said backing material over the rear surface of said shell, hardening said backing material to form an electrotype plate, compressing the rear surface of the electrotype plate by slowly rotating the electrotype plate in said cylindrical drum, applying roller pressure upon a small area of the backing material of said electrotype plate while rotated, and slowly moving said roller axially throughout the width of said electrotype plate, thereby forming a helical groove throughout the entire rear surface of the backing material, and adjusting the pressure applied to said roller to meet the requirements of pressures needed.

5. Apparatus for producing curved electrotype plates and compressing the same, said apparatus including 2]. cylindrical drum for receiving the electrotype shell on its interior surface, means for applying backing material to said electrotype shell, means for rotating said drum, means for producing pressure on said backing at a selected area, and means for moving said pressure producing means axially while the drum is rotating so as to produce a close helical condensed pathway throughout the surface of said backing material.

6. Apparatus for producing curved electrotype plates and compressing thesame, said apparatus including a cylindrical drum for receiving the electrotype shell on its interior surface, and for receiving backing material on the rear surface of said electrotype shell, means for rotating said drum, means for producing pressure on said backing material at a selected area while the drum rotates, said means comprising a pressure roller mounted for travel on the interior curved surface of said backing material in a pathway substantially along a circumference of said backing material, and means for moving said pressure roller axially to produce a close helical condensed pathway throughout the entire rear surface of said backing material.

7. Device for compressing backing metal onto the surface of a curved electrotype plate to compress the backing material thereof, said device including a cylindrical drum for receiving an electrotype shell on its interior surface and for containing the molten backing material, means for rotating said drum at a speed suflicient to evenly distribute the backing material by centrifugal force to cast the same on the rear of the shell, a pressure roller mounted for travel along a substantially circumferential path as the drum is rotated at a slower speed than when casting, means for moving said roller in an axial direction to produce a compressed path on the curved inner surface of said backing, and means for selectively adjusting the pressure on said pressure roller.

References Cited in the file of this patent UNITED STATES PATENTS 385,752 Gould July 10, 1888 2,055,171 Dailey Sept. 22, 1936 2,309,126 Lundius Jan. 26, 1943 2,537,604 Ricards et a1. Jan. 9, 1951 2,604,017 Crafts et al. July 22, 1952 2,618,182 Teetor Nov. 18, 1952 

